Internal combustion engine



May 13, 1941. T. E. HULL INTERNAL COMBUSTION ENGINE Filed April 16, 1940 3 Sheets-Sheet 1 May 13, 1941. HU 2,241,910

INTERNAL COMBUSTION ENGINE Filed April 16, 1940 :5 Spets-Sheet '2 T. E. HULL INTERNAL COMBUSTION ENGINE May 13, 1941.

Filed April 16, 1940 3 Sheets-Sheet 3 Patented May 13, 1941 UNITED STATES PATENT OFFICE INTERNAL COMBUSTION ENGINE Thomas E. Bull, Oakland, Calif. Application April .16, 1940, Serial 'No. 329,899

6 Claims.

The invention relates to internal combustion engines and more particularly to the combustion chamber construction and fuel injection system of such engines.

An object of the invention is to provide an internal combustion engine of the character described wherein the fuel will be introduced into the combustion chamber of the engine during or at the end of the compression stroke of the engine and into a medium of hot quiescent compressed air and wherein the fuel is introduced in a rich hydroxylated air and fuel mixture whereby the admixture, distribution and burning of the fuel will be more uniform and with less tendency to detonate than in previous combustion engines, all cooperating to produce an increased efliciency and power output of the. engine.

Another object of the invention is to provide an internal combustion engine of the character above which will effect a substantial simplification and reduction of number of parts and will effecta complete elimination of the usual electric ignition system of the common Otto cycle type engine.

A further object of the invention is to provide an internal combustion engine of the character above which readily lends itself to an opposed double-acting piston and cylinder type of construction affording a simplification and compactness of parts and a better balance and distribu tion of stresses in the engine.

The invention possesses other objects and features of advantage, some of which, with the foregoing, will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of the specification. It is to be understood, however, that variations in the showing made by the said drawings and description may be adopted within the scope of the invention as set forth in the claims.

Referring to said drawings:

Figure 1 is a vertical cross-sectional view of an engine constructed in accordance with the present invention.

Figure 2 is a vertical cross-sectional view of the engine taken at substantially right angles to the plane of Figure 1 and as indicated by line 2-2 of Figure 1.

a Figure 3 is a plan view'of the engine with the top cover plate thereof removed.

Figure 4 is an enlarged vertical sectional view of the fuel injection passage and valve therein.

Figure 5 is a horizontal cross-sectional view of the engine taken substantially on the plane of line 5-5 of Figure 1.

Figure 6 is a horizontal cross-sectional view taken substantially on the plane of line 66 of Figure 1.

Figure 7 is a vertical cross-sectional view of the several operating cams, each shown sepa-,

fuel and air or exhaust gas which is ignited uponadmixture with the hot quiescent air in the chamber at the end of the compression stroke without the required assistance of a spark or other ignition means. The gaseous air and fuel mixture is preferably received and compressed and injected into the main engine chamber aforementioned by means of an auxiliary compressor unit operated jointly and in timed relation with the main engine piston and cylinder unit above.

With reference to the accompanying drawings,

and more particularly to Figures 1 and 2, the internal combustion engine herein illustrated is of I the opposed double acting piston and'cylinder type, including upper and lower stationary pistons -II and I2, which are arranged in longitudinal alignment and are embraced by cylindrical bores i3 and i4 provided in a casing member IS. A cross partition I! in the member 16 separates the cylinders i3 and I4 and provides closed ends therein which cooperate with the heads II and IQ of the pistons to define engine chambers M and 22 which vary in size upon reciprocation of the member IE to provide the expansion and compression strokes of an internal combustion engine. As will be clear from the type oi. structure here illustrated, the upper compartments 21 will be compressed while the lower compartment 22 is expanded and throughout the operating cycles of the two engine units the units will be 180 out of phase with each other, relative to crank shaft rotation. This out of phase relationship of the units and the direct longitudinal alignment of the compartments provides an improved balance and distribution of operating stresses as well as a ing medium through the piston.

simplification and a reduction of parts providing the engine cylinders in a single sliding sleeve casing.

Valve and passage means is provided for each of the compartments 2| and 22 for'introducing 'air into the compartments for compression and for exhausting the spent combustion products at the end of the power stroke. As an important feature in the present construction, such passage and valve means is incorporated directly in the pistons II and I2, whereby the valve and passage assembly and the several operating parts for the valve may be supported on a stationary part of the engine without interfering with the relative movement of the sleeve l6. As will be best seen from Figures 1, 2, 5 and 6, each of the pistons II and I2 is divided by a pair of transverse longitudinally extending interior walls 23 and 24 to define in conjunction with the side cated with circular valve seats 3| and 32 which are engaged'by exhaust and intake poppet valves 33 and 34. These valves are provided with stems 36 which extend through longitudinal openings or bores 31 in the piston and are normally drawn to a closed position against. seats 3| and 32 by means of helical valve springs 38 which are compressed between a spring seat 39 on the free end of the stem and a spring seat 4| carriedby the body portion of the piston.

In operation of the engine the exhaust and intake valves 33 and 34 of each of-the engine units are open during one stroke, or 180, of the cycle relative to crank shaft rotation in the conventional manner, whereby the intake valve is open during a suction stroke for the intake of air and is closed during the compression, power and exhaust strokes of the cycle, and the exhaust valve is open following the power stroke for the discharge of the spent combustion products for '180" of crank shaft rotation and is closed during the intake compression and power strokes. Means for so opening and closing these valves is here embodied in the form of a cam shaft 42 which is operatively connected to the crank shaft of the engine so as to rotate the cam shaft at one-half crank shaft speed. The cam shaft is here rotatably supported across the top of the piston II and carries cams 43 and 44 which bear directly upon the spring seats 39 at the upper ends of the stems of valves 33 and 34. The lower intake and exhaust valves 33 and 34 are operated by cams 46 and 41 mounted on the cam shaft 42 and operatively connected by rocker arms 48 and 49 with rods 5| and 52 which extend vertically exteriorly of the sleeve member l6 and are connected at their lower ends with rocker arms 53 and 54 which are carried on sleeves 56 and 51 on a shaft 58'journaled across the bottom of the lower piston and on which sleeves are secured to arms 59 and 6|, which in turn engage the lower ends of spring rests 62 and 63 engaging the lower ends of stems of valves 33 connecting rods 64 and 66 which are journaled on bearing pins 61 and 68 carried by the exterior of the sleeve member adjacent the partition and which are operatively connected at their opposite ends to the crank shaft of the engine (not shown). I

As explained above, the fuel is injected into the engine compartments 2I- and 22 preferably in air in the compartments for supporting combustion. In accordance with the present construction the rich fuel mixture is received and compressed and fed into the main engine chambers by means of auxiliary compressor units which are preferably of the piston and cylinder type. The fuel mixture is compressed in a rich state in the presence of an insuflicient quantity of oxygen to support combustion. As here shown. with particular reference to Figure 1, I provide a pair of stationary pistons 69 and 1| adjacent and parallel to the pistons II and l2 and these auxiliary pistons are embraced by cylindrical bores 12 and I3 formed in the reciprocating sleeve member l6; As will be seen from Figure 1, the piston 69 is parallel to and is of approximat'ely the same length as piston whereas piston II is parall l to and approximately of the same length a piston |2and pistons 69 and II are in longitudinal alignment. The chamber I4 is de-' fined between the head end 16 of piston 69 and a partition portion I1 of the sleeve member separating the cylinders 12 and I3 and a similar compartment 18 is defined between the head end 19 of piston 1|" and the partition 11. Upon reciprocation of the sleeve member I 6, the compartment '|4 be compressed simultaneously with the compartment 2| and at the same time compartment 18 will be expanded simultaneously with .the compartment 22. On the next sueceeding stroke of the sleeve member the com-- pression and expansion of the compartments will be reversed.

During the expansion stroke of each of chambers 14 and 18 corresponding with the'intake stroke of chambers 2| and 22, a rich gaseous air and fuel mixture isdrawn into the chamber and upon the following compression stroke of the chamber this mixture is compressed to a pressure somewhat higher than the pressure obtained in the adjacent chamber 2| 'or 22 at the end of its compression stroke and the mixture is caused to flow under this pressure differential from the auxiliary chamber into the main engine chamber. The flow of the air and fuel mixture from the chambers 14 and 18 to the cylinders 2| and 22 is dependent upon the relative pressures in the chambers. The flow is substantially con fined to the end of the compression stroke due to rapid motion of the sleeve adjacent the central portion of its stroke and the following temperature rise and further pressure rise caused by the temperature rise.

The pistons 69 and H are formed with longitudinal interior passages BI and 82 which are adapted" for connection exteriorly of the engine to a source of gaseous air and fuel mixture. Such a source may be obtained from a carburetor or other fuel and air mixing mechanism. The opposite ends of the passages 8| and 82 terminate'in circular valve seat openings and 85 in the heads 16 and 19 of the pistons, and these openings are opened and closed by poppet type ralves 83 and 84 carried by the pistons. In iperation, these valves are open during three of be four operating strokes and are closed during ;he compression stroke of the chambers 14 and 18 corresponding with the compression stroke of :hambers 2| and 22. Thus on the intake stroke if the engine, air and fuel mixture is drawn into zhe chambers 14 and 18 which is compressed on ;he succeeding compression stroke for passing nto the adjacent engine compartments. The )pening and closing of the valves 83 and 84 is arranged to be effected in timed relation to the movement of the sleeve member l6, by operating these valves from cams 93 and 94 on the cam shaft 42. Cam 94 is positioned adjacent the right end of the cam shaft, with reference to Figure 2, and engages a rocker arm 98 carried by a sleeve 91 on an auxiliary shaft 98 paralleling the cam shaft 42. An arm 99' carried by the sleeve 91 engages the upper end of the stem of auxiliary chambers into the adjacent engine chambers by way of passages formed in the partition member 11 which communicates the head end of the cylinders 12 and I3 with the head ends of cylinders l3 and I4. Injection nozzles 86 and 81 are mounted in these'passages. One of these nozzles is illustrated in enlarged form in Figure 4 of the drawings, wherein it will be seen that the member 88 is provided over an interior portion of its length with an axial passage 88 which is connected by a side port 89 to the head end of the auxiliary cylinder and which discharges at its interior end 9| into the head end of the engine cylinder.

As an important feature of the present construction, and as aforementioned, the pressure generated in the auxiliary chambers 14 and I8 is somewhat greater than the pressure generated on the compression stroke of the compartments 2| and 22, so as to cause a gaseous flow from the auxiliary chambers into the main engine chambers. This is here effected by arranging the auxiliary cylinders and pistons with a larger compression ratio than the main engine and piston cylinders. As will be seen from Figure 1, this effect is here obtained by providing a greater clearance between the heads of pistons II 'and I2 and the end wall I! than between the heads of pistons 89 and H with the end wall 11. The increased compression ratio in the auxiliary compartments l4 and 18 produces an increasing rise in pressure towards the end of the compression stroke whereby the majority of the compressed air and fuel mixture will pass into the engine chambers adjacent to the end of the compression stroke in such chambers, and thereby insuring ignition only adjacent the end of such compression strokes. Also preferably,'the compression ratio of the main engine units is such that a self-ignition temperature will be reached only adjacent the ends of the compression stroke.

In order to obtain a uni-directional flow of gas from the auxiliary chambers into the main engine chambers, I prefer to incorporate a check valve 92 in the interior passage 88 of the nozzles 88 and 81 which will. close the passage upon ignition of the fuel in the main engine chamber.

The operation of the engine, as will be understood from the foregoing, may be summarized as follows. With reference to Figure 1 and assuming that chamber 2| is about to start its power stroke, chamber 22 is about to start its exhaust stroke. Accordingly the intake and exhaust valves in piston II are closed and the exhaust valve in piston I9 is open. As the sleeve moves downwardly, with reference to Figure l, the gases in chamber 22 are exhausted through passage 21 and the gases in chamberv 2| expanded during the power stroke of the engine. 'At the end of this downward stroke of the sleeve, the exhaust valve opens in the top compartment and the intake valve opens in the bottom compartment and the gases are exhausted from the upper compartment while air is introduced into the lower compartment. On the following down stroke of the sleeve, the intake valve opens in the top chamber to admit air while the air which was taken into the lower compartment during the preceding stroke is compressed. During this stroke the valve 84 in the auxiliary compartment 18 is seated and the fuel mixture is compressed in the chamber 18. The mixture thus compressed in chamber 18 is passed through the injection nozzle 86 into the chamber 22 and ignition takes place adjacent the end of the down stroke of the sleeve. The check valve 92 then closes in the passage 88 communicating the auxiliary and main engine chambers to hold the burning and pressure in the main chamber 22. During the following upward movement of the sleeve the power stroke takes place in the lower compartment 22, while the compression stroke takes place in the upper compartment 2|. During three of these four strokes including the power stroke, the exhaust stroke and the intake stroke; valves 83 and 84 in the auxiliary compartments remain open, and these valves are closed during the compression stroke so as to cause a passage of mixture into the main engine cylinders, as above described. The several cams 43, 44, 46, 41, 93 and 94 are illustrated in their co-related positions in Figure 7. Inasmuch as the-cam shaft is operated at one-half crank shaft speed, the lift portions of the intake and exhaust cams 43, 44, 48 and 41 cover of rotation of the cam shaft, corresponding with of rotation of the crank shaft. In the case of the cams 93, 94 for the fuel valves, the lift portions subtend approximately 270 of the cam periphery. The cams are illustrated in Figure 7 in their position at the end of the compression stroke in the upper compartment, and the end of the power stroke in the lower compartment. While the engine is here arranged for four cycle operation, it will of course be understood that the same may be arranged with equal facility fortwo cycle operation by merely changing the shape and speed of rotation of the series of cams, so as to provide an intake, compression, power and exhaust operation during each reciprocation of the sleeve.

An important feature of the device resides in the fact that at throttled speeds, the fuel injection is automatically delayed and combustion retarded as is desirable at slow speeds and starting.

Throttling is preferably accomplished by use of a butterfly valve (not shown) in the fuel intake passages. 8| and 82,so that when the throttle is partially closed, a partial vacuum will be drawn in the chambers 14 and 18 which will then contain only enough gaseous fuel to operate the engine at reduced speed. Consequently during the compression stroke on the gases contained in chambers 14 and 18, the pressure will not be built up sufilciently to cause flow into the main engine cylinder until relatively late inthe compression stroke. v

The engine construction here illustrated utilizing the opposed piston and cylinder arrangement, provides many advantages in the reduction of parts necessary and in obtaining a. better distribution of stresses within the. engine. The ma- J'ority of stress insofar as the sleeve is concerned, is at the mid portion thereof adjacent the cross partition and the bearing pins 61 and 68. Accordingly, I prefer to use a greater wall thickness at the central portion of the sleeve and reduce the wall thickness towards the opposite open ends of the sleeve.

As a modified form of the invention I may positively withhold the passage of compressed air and fuel mixture from the auxiliary chambers 14 and 18 into the main engine chambers 2| and 22 until adjacent the end of the compression stroke. This may be effected, as illustrated in Figure 8, by the provision of a spring pressed check valve 92' in the passage 88' provided in the nozzle member 86' and communicating the auxiliary and main engine chambers. As shown in Figure 8, a helical spring N14 is mounted ahead of the valve 88' for urging the latter to its seated position in the passage and the tension of the spring is fixed to prevent the opening of the valve until adjacent the end of the compression stroke.

I claim:

1. An internal combustion engine comprising, a plurality of stationary pistons, a plurality of cylindrical sleeve members reciprocally embracing said pistons, means for jointly reciprocating said cylinders longitudinally relative to said pistons for compressing and expanding a chamber defined between each of the heads of said pistons and closed ends of said cylinders, valve and passage means connected to one of said chambers and operated in timed relation with the change of volume thereof for introducing air into said chamber and-venting spent combustion products therefrom, valve and passage means connected to the other of said chambers for introducing a rich gaseous'fuel and air mixture into said second chamber for compression therein,

. said second chamber having a higher compresvolume of said chambers, valve and passage means connected to one of said chambers and operated in timed relation with the movement of said member for introducing air into said chamber during an enlarging stroke thereof and sealing said chamber during a compression and power stroke thereof and venting spent combustion products from the chamber during a volume reducing stroke thereof, valve and passage means connected-to the other of said chambers and operated in timed relation to the movement of said member for introducing a rich gaseous fuel compression of the mixture therein, said second chamber having a higher compression ratio than said first chamber, and passage means connecting said chambers for passing compressed mixture from said second chamber into compressed air into said first chamber.

3. An internal combustion engine comprising, a pair of stationary pistons mounted in parallel relation to each other, a member formed with a pair of parallel cylindrical bores slidably embracing said pistons and defining chambers between the heads of said pistons and the inner ends of said bores, means for reciprocating said member relative to said pistons for varying the volume of said chambers, valve and passage means connected to one of said chambers and operated in timed relation with the movement of said member for introducing air into said chamber during an enlarging stroke thereof and sealing said chamber during a compression and power stroke thereof and venting spent combustion products from the chamber during a volume reducing stroke thereof, valve and passage means connected to the other of said chambers and operated in timed relation to the movement of said member for introducing a rich gaseous fuel and air mixture into said second chamber for compression of the mixture therein, said second chamber having a higher compression ratio than said first chamber, passage means connecting said chambers for passing compressed mixture from said second chamber into compressed air into said first chamber, and a check valve in said last named passage means providing a unidirectional flow of fluid from said second chamber to said first chamber.

4. An internal combustion engine comprising, a pair of stationary pistons mounted in parallel relation to each other, a member formed with a pair of parallel cylindrical bores slidably embracing said pistons and defining chambers between the heads of saidpistons and the inner ends of said bores, means for reciprocating said member relative to said pistons for varying the volume of said chambers, valve and passage means incorporated in one of said piston heads a and communicating with the chamber defined and air mixture into said second chamber for thereby and operated in timed relation with the movement of. said member for-introducing air into said chamber during an enlarging stroke thereof and sealing said chamber during a compression and power stroke thereof and venting spent combustion products from the chamber during a volume reducing stroke thereof, valve and passage means incorporated with the other of said piston heads and registering with the chamber defined thereby and operated in timed relation to the movement of said member for introducing a rich gaseous fuel and air mix ture into said second chamber for compression of the mixture therein, said second chamber having a higher compression ratio than said first chamber, and passage means connecting said chambers for passing compressed mixture from said second chamber into compressed air 'into said first chamber.

5. internal combustion engine comprising, a relative reciprocating piston and cylinder unit defining an engine chamber of variable size for;

carrying out the expansion and compression strokes of an internal combustion engine cycle,

spent combustion products therefrom, a second relative reciprocating piston and cylinder unit defining a chamber of varying volume and operated in synchronism with said first unit, means for introducing a rich fuel and air mixture into said second chamber for compression of the mixture therein, said second chamber having a higher compression ratio than said first chamber, and valve and passage means connecting said chambers and operative to withhold compressed mixture in said second chamber until adjacent the end of the compression stroke of both of said chambers and then to pass compressed mixture from said second chamber into compressed air in said first chamber.

6. An internal combustion engine comprising, a relative reciprocating piston and cylinder unit defining an engine chamber of variable size for carrying out the expansion and compression strokes of an internal combustion engine cycle, valve and passage means connected to said chamber and operated in timedrelation with the change in volume of said chamber for introducing .air into said chamber and venting spent combustion products therefrom, a second relative reciprocating piston and cylinder unit defining a chamber of varying volume and operated in synchronism with said first unit, means for introducing a richfuel and air mixture into said second chamber for compression of the such flow until approximately the end of the compression stroke.

, THOMAS E, HULL. 

